Meeting "Girl Friends"

So tonight I'm supposed to go to dinner with hotdoc and some of his friends. One in particular is this girl who he works with (some nurse) who he has a bit of bizarre relationship with. Apparently she's really attractive (I've seen pics-- it's true) and a lot of people at the hospital thought they were hooking up even though they weren't, she has a serious long-term boyfriend. Needless to say I've been warned by hotdoc that she is super controlling and attached to him in a "friend" way (whatever that means...) and whenever he starts dating a girl she will instantly declare no one is good enough for him. Ok. Let's evaluate. How the hell am I supposed to take this news? I'm not exactly excited to meet this girl who I already have a preconceived notion is a huge bitch. How am I supposed to act? I should be myself of course-- but should I try to look super cute or will that be intimidating to her? If I don't look cute she might just think I'm this dumpy girl. How do I win? Do I joke around or be completely serious? I hate meeting other girls. Especially one's who feel a sense of entitlement with their guy friends. Hello-- you aren't dating him, back the f off! I'm the complete opposite with my guy friends. I push them into hooking up with my hot girlfriends (aren't I such a nice person???) Needless to say I don't think I should have to go through an interview process to impress someone that I don't particularly care about. Or should I be more concerned since it's a good friend of hotdocs? Sigh. Help.